Compressed-gas circuit interrupters using one gas for interruption and another gas for isolation



yzw a Oct. 26, 1965 R. G. COLCLASER, JR.. ETAL 3,214,543

COMPRESSED-GAS CIRCUIT INTERRUPTERS USING ONE GAS FOR INTERRUPTION AND ANOTHER GAS FOR ISOLATION Filed Dec. '7. 1960 4 Sheets-Sheet 1 72 l v a I3 I 6 U2 J2 J2 Fig.l W f I HIGH PRESSURE COMPRESSED AIR ,Jl 4 4 5 OPERATING wflM////// fl/Q MECHANISM Fig.2

WITNESSES |NVENTORS Robert G. Colcloser,Jr.

8 Frank L. Reese ATTORNEY Oct. 26, 1965 R. G. COLCLASER, JR.. ETAL 3,214,543

COMPRESSED-GAS CIRCUIT INTERRUPTERS USING ONE GAS FOR INTERRUPTION AND ANOTHER GAS FOR ISOLATION Filed D90. 7, 1960 4 Sheets-Sheet 2 HIGH PRESSURE O 6, 1965 R. e. COLCLASER, JR.. ETAL 3,

COMPRESSED-GAS CIRCUIT INTERRUPTERS USING ONE GAS FOR INTERRUPTION AND ANOTHER GAS FOR ISOLATION Flled Dec 7, 1960 4 Sheets-Sheet 3 3 6 w :82 m2 5:; $5255 QESHME 5:2: 6 m3 0 L 1965 R. G. COLCLASER, JR.. ETAL 3,214,543

COMPRESSED-GAS CIRCUIT INTERRUPTERS USING ONE GAS FOR INTERRUPTION AND ANOTHER GAS FOR ISOLATION Filed Dec. 7. 1960 4 Sheets-Sheet 4 Fig. IO

United States Patent 3,214,543 COMPRESSED-GAS CIRCUIT INTERRUPTERS USING ONE GAS FOR INTERRUPTION AND ANOTHER GAS FOR ISOLATION Robert G. Colclaser, Jr., Monroeville, and Frank L. Reese, Wilkinsburg, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Dec. 7, 1960, Ser. No. 74,366 12 Claims. (Cl. 200-148) This invention relates to circuit interrupters in general and, more particularly, to compressed-gas circuit interrupters of the type employing a blast of gas to effect arc extinction.

In United States patent application filed November 18, 1959, Serial No. 853,974, now United States Patent 3,114,815, issued December 17, 1963, to Robert L. Hess, James M. Telford and Gilbert I Easley there is disclosed and claimed a puffer-type of circuit-interrupting structure including a grounded mechanism housing supported up in the air, and having extending outwardly from opposite ends of the mechanism housing a pair of weather-proof casings, axially of which extends the conducting structure for the circuit interrupter. In the aforesaid patent application a crank-arm was associated with the grounded mechanism housing, and the crank-arm effected not only the opening and closing movement of the contact structure, but also the movement of a puffer cylinder over a relatively stationary piston to compress gas, and to eject the same through an orifice into immediate proximity with the established arc. It is, accordingly, a purpose of the present invention to improve upon the general line of circuit-interrupting structures, such as set forth in the aforesaid patent application, rendering the same more economical in performance by using, instead of sulfur hexafluoride (SP gas as the interrupting medium, ordinary economical compressed air, while at the same time retaining the advantages of sulfur-hexafiuoride gas as the dielectric medium in the casing surrounding the interrupting unit.

Yet a further object of the present invention is to provide an improved circuit-interrupting structure in which compressed air is employed as the interrupting medium, and in which a high-dielectric-strength gas, such as sulfur-hexafluoride (SF gas, selenium-hexafluoride (SeF gas, C F CF SF may be employed as the dielectric gas adjacent the disconnecting contact structure.

Another object is to provide an improved compressedair circuit interrupter in which the compressed air is not only used for interrupting purposes, but also for insulation strength at serially-related disconnecting means.

Yet a further object of the present invention is to provide a multi-pole circuit-interrupting structure in which the several poles may be simultaneously actuated to both the open and the closed-circuit positions.

Yet a further object of the present invention is the provision of an improved compressed-gas circuit interrupter in which the opening operation is achieved by pneumatic means, and in which the closing operation is mechanically brought about by mechanical means.

A further object of the present invention is to provide an improved line of circuit-interrupting structures employing compressed air as the interrupting medium, and being adaptable, with only slight modification, for use with a resistor, or other impedance means for interrupting the higher powers.

Further objects and advantages will readily become apparent upon reading the following specification, taken in conjunction with the drawings, in which:

FIGURE 1 is an end elevational view of a three-phase circuit-interrupting assembly embodying features of the present invention;

FIG. 2 is a fragmentary view, similar to that of FIG. 1, but illustrating the mounting arrangement for a circuitinterrupting structure of lower voltage rating, employing a single tank instead of three separate tanks;

FIG. 3 is a side elevational view of the structures of either FIG. 1 or FIG. 2;

FIG. 4 is a fragmentary longitudinal sectional view taken through one of the pole-units of FIG. 1, the contact structure being illustrated in the closed-circuit position and a diagrammatic view of the operating mechanism;

FIG. 5 is a considerably enlarged, longitudinal vertical sectional view taken through the interrupting structure for the circuit interrupter of the present invention, the contact structure being illustrated in the closed-circuit position;

FIG. 6 is a fragmentary detailed view of the crankoperating mechanism of the present invention;

FIG. 7 is a fragmentary detailed plan view taken substantially along the line VIIVII of FIG. 6;

FIG. 8 is a detailed fragmentary view of the blast-tube connection illustrating the provision for affording leakage of high-pressure gas to the atmosphere;

FIG. 9 is an enlarged end elevational view of the contact finger arrangement for the stationary guide post of the interrupting unit taken along the line IX-1X of FIG. 5;

FIG. 10 is a detailed fragmentary view taken substantially along the line XX of FIG. 9; and

FIG. 11 is a fragmentary plan View of a modified type of interrupting unit employing a shunting impedance.

Referring to the drawings, and more particularly to FIG. 1 thereof, the reference numeral 1 generally designates a three-pole circuit interrupter including a plurality of pole-units A, B and C. As shown, the pole-units are mounted at the upper extremity of a metallic grounded blast tube 2, which extends upwardly from a lower compressed-gas reservoir tank 3. Tank 3 is mounted upon channel members 4 on a suitable base 5.

Interconnecting the pole-units A, B and C are horizontally-extending braces 6, 7. In addition, a horizontallyextending enclosing operating tube 8 encloses a rotatable operating shaft 9 more clearly shown in FIG. 4, and mechanically connected to the three pole-units so as to insure simultaneous operation of the contact structures.

Disposed at one end of the high-pressure reservoir chamber 3 is an operating mechanism housing 10 containing a suitable operating mechanism, such as one, for example, of the pneumatic type 11, as shown in FIG. 4. In addition, if desired, an auxiliary storage tank 12 containing a highly efficient dielectric gas, such as sulfurhexafluoride (SF gas, may be employed to feed such high-dielectric-strength gas through a pipe 13 to the mechanism housings 15 about the pole-units A, B and C by way of the enclosing tube 8 for the operating shaft, hereinafter described. The circuit interrupter 1, as illustrated in FIG.' 1, is adaptable for a voltage range, for example, 69 kv. For a lower voltage range, for example, 34.5 kv., the several mechanism housings .15 of the several pole-units A, B, C may be combined into a single tank 15A, as shown in FIG. 2 of the drawings.

With reference to FIG. 4 of the drawings, it will be noted that disposed interiorly within the mechanism housing 15 is an interrupting unit 16 supported upon an insulating blast tube 17. The interrupting unit 16 includes an exhaust-chamber portion 18, an insulating casing portion 19 and a high-pressure storage-tank portion 20, as shown more in detail in FIG. 5 of the drawings.

Extending laterally of the mechanism housing for each pole-unit is a pair of oppositely-disposed insulating casings 21, preferably of Weather-proof material, such, for example, as porcelain. Secured to the opposite external ends of the weather-proof casings 21 are line terminals 22, which may be employed to connect the controlled external circuit to the circuit-interrupter pole-units A, B and C. Extending coaxia lly through the right-hand weatherproof casing 21, as shown more clearly in FIGS. 4 and 5, is a conducting exhaust tube 23. The exhaust tube 23 communicates with the atmosphere 24 externally of the pole units, as shown in FIG. 3, preferably an exhaust deflector 25 being provided, the purpose for which will be more clearly brought out hereinafter. Extending coaxially through the left-hand weatherproof casing 21 is a relatively stationary con-ducting rod 26, the inner end 27 of which constitutes a relatively stationary disconnecting contact. Cooperable with the relatively stationary disconnecting contact 27 is a second relatively stationary disconnecting contact 28 of rod-like configuration, which is secured, as by bolts 29, to a boss portion 30 of the casting 20 comprising the high-pressure reservoir chamber of the unit 16.

A movable bridging disconnecting contact 31 is secured to the outer free extremity of a rotatable crank-arm 32 secured to, and rotatable with, the operating shaft 9, as indicated in FIG. 4 of the drawings.

As mentioned, the rotatable operating shaft 9 is enclosed within the gas-tight tube 8, which connects at one end thereof with feed tube 13 for the SP container 12. Thus, the SP gas is communicated to all three casings 15 by way of the enclosing tube 8.

From the foregoing description, it will be apparent that the circuit through the circuit interrupter 1 extends generally from line terminal L to left-hand line connector 22, stationary conducting rod 26, disconnecting contact bridge 31, conducting rod-portion 28, conducting casting 20, conducting guide post 33, spring fingers 34 (FIG. 9), flexible conductors 35, bolts 36, blast valve 37, relatively stationary blast valve seat 38, flange portion 39, exhaust chamber 18 to the conducting exhaust tube 23. The circuit then extends through the exhaust tube 23 to the righthand line terminal 22 and thence to the external line L As shown in more detail in FIGS. 9 and 10, the spring fingers 34 are biased inwardly by compression springs 34a encircling spring rods 34b. Heads 340 on the rods 34b are captively held in recesses 34d.

Compressed gas, for instance, compressed air is under pressure within the lower exhaust tank 3, as illustrated in FIG. 1. This high pressure is communicated through the feed tubes 2 to the high-pressure chamber 20 within each of the interrupting units 16. At times, the blast valve 37 is operable toward the left, as viewed in FIG. 5, to permit the exhausting of high-pressure gas from the region 40 through the annular passageway 41 and out through the orifice opening 42 into the exhaust chamber 43 and out through the exhaust tube 23. This exhausting of the gas from high-pressure chamber 40 is controlled by operation of the blast valve 37, as is obvious from an inspection of FIG. 5 of the drawings.

To effect the leftward opening movement of the blast valve 37, against the biasing action exerted by the compression spring 44, the region 45, in back of the blast- Valve piston 46 is dumped to atmospheric pressure through an exhaust tube 47 by actuation of electro-magnetically actuated valve 48 (FIG. 4). Thus, energization of the solenoid 49 by closing the opening, or trip button 50, will energize the coil 49 and so attract the armature 51 of the valve 48 upwardly to open the exhaust outlet 52 associated therewith. This will dump the pressure through the exhaust tube 47, and consequently the region 45 in back of the blast-valve piston 46. Since high pressure exists within the region 53 through the ports 54, the blast-valve piston 46 will be quickly forced to the left, as viewed in FIG. 5, permitting an exhaust-ing of high-pressure gas, such as compressed air, through the orifice 42, and out through the exhausttube 23 freely to the atmosphere 24 (FIG. 3).

Since the connected circuit extends between the movable blast-valve 37 and the blast-valve seat 38, an arc (not shown) will be drawn therebetween, which, because of the radially inwardly extending blast of compressed air, will be transferred to the .apertured arc horn 55 and the tip portion 56 of the movable contact 38. The radially inwardly extending compressed-air blast will quickly effect extinction of the are, not shown, and the circuit will, consequently, be interrupted. With reference to FIG. 4, it will be observed that closing of the trip button 50, bridging the contacts 76, will also energize the coil 77 of the latching device 78. The energizing of the coil 77 will move the catch rod to the right thereby releasing the catch 74a associated with piston rod 74. This will, in turn, permit the accelerating opening spring 63 to effect upward movement of the piston 61 and consequent clockwise opening rotation of the crank-arm 73. The piston 61 moves reciprocally within an operating cylinder 62.

To cushion the moving blast-valve piston 46 at the end of its fully open travel, a bumper, generally designated by the reference numeral 65, is employed. The bumper 65 comprises a plurality of resilient washers 66- having suitable openings 66a provided therein to accommodate the stationary contact post 33, and also openings 67, which register to form an exhaust passage 68, which communicates with the exhaust tube 47. As a result, at the end of the opening operation of the blast-valve 37, the blastvalve 37 will be brought to a cushioned halt.

From the foregoing description, and by way of recapitulation, to effect opening of the circuit interrupter 1 the opening, or trip valve 50 is pressed. This will energize electromagnetic valve 48. The energizing of valve 48 will dump the high-pressure gas in the region 45, in back of the blast-valve piston 46, through the exhaust pipe 47. This will effect separation of the contact structure 37, 38 and exhausting of high-pressure gas through the orifice opening 42 and out of the interrupting chamber 16 through the exhaust tube 23, which communicates to atmosphere 24 (FIG. 3).

The are will be quickly extinguished, and upon subsequent closure of the valve 48, high-pressure gas, leaking through the openings 71 (FIG. 5), will raise the pressure within the region 45 to effect reclosure of the blastvalve 37, this action being assisted by the compression spring 44. In the meantime, however, the energization of coil 77 has resulted in upward movement of th operating piston 61, which effects, through the thrust rod 72 rotation of the bell-crank 73, and consequent clockwise opening rotation of the operating shaft 9, which interconnects the three-pole units A, B and C. Because of the overlapping of the bridging contact 31 with the bifurcated portions 27a, 28a of the relatively stationary disconnecting contacts 27, 28 respectively, the are, drawn within unit 16, will have been extinguished by the time that a' disconnecting gap is formed. The maintenance of the disconnecting gap will insure that the circuit L L will remain open, even though the contact structure 37, 38 reclose due to the spring pressure 44 and equalization of gas pressure between the regions 45, 41 through the holes 71.

To effect the reclosing of the circuit L L through the interrupter 1, a closing button 64 is pressed downward energizing the electromagnetically actuated valve 57 to effect transmission of high-pressure gas from the tank 3 through an inlet pipe 58, through the valve 88, and through an inlet pipe 59 to the top side 60 of the operating piston 61. This moves the piston 61 downward effecting counterclockwise closing rotation of the crank arm 73. At the end of the closing operation, the piston rod 74 is latched at the catch 74a by the latch 75.

The counterclockwise rotation of the crank-arm 73 will, correspondingly, effect counterclockwise rotation of the several movable disconnecting contact arms 32, to bridge the spaced relatively stationary disconnecting contacts 27, 28 of the pole-units A, B and C, thereby effecting contact closure and circuit continuity through the pole-units.

For very high-power applications, the interrupting unit 16 may be modified, as illustrated in FIG. 11, to incorporate an impedance 80, which shunts the castings 18, 20. As a result, the residual current passing through the modified-type interrupter 81 will be opened at the series disconnecting gap 27, 31 in an obvious manner.

From the foregoing description of the invention, it will be apparent that there has been provided a novel compressed-gas type of interrupting unit, in which a relatively cheap gas, such as air, may be compressed and utilized for interrupting purposes. To minimize the length of the arc drawn during the closing operation, a relatively high-dielectric-strength gas, such as sulfur-hexafluoride (SP gas may be employed in the chamber adjacent the disconnecting contact structure. The use of SE, also permits a dead-tank structure of minimum dimensions. An economical design is obtained because a relatively low pressure is required for voltage insulation, resulting in a relatively light tank construction.

For certain inexpensive applications, compressed air from the tank 3 may be substituted for the SE, in the disconnecting region 14. At tank pressure th insulation value is improved.

Current transformers 84 (FIG. 3) may be employed, encircling the grounded flange collars 85, to ensure that any internal fault condition associated with the circuit interrupter 1 will pass to ground between the two current transformers 84, and be reflected as an internal fault in operating associated protective relaying equipment. Reference may be had to United States patent application filed March 31, 1958, Serial No. 725,286 now United States Patent 3,032,689, issued May 1, 1962, to Benjamin P. Baker and Robert F. Karlicek, and assigned to the assignee of the instant application for a description of the associated protective relaying circuits. For the particular applications where such protectiv relaying is not desired, and only a single current transformer 84a is to be employed, the mounting for the current transformer 84a may be as set forth in FIG. 11 of the drawings, where, as shown, it encircles the central portion of the metallic housing 15 of the interrupter 1. In this particular case, the current transformers 84a would serve merely a currentmeasuring function.

It will, therefore, be apparent that the circuit-interrupting structure 1 of the present invention, may be employed in a complete line of breakers depending upon the voltage and current rating. For the lower voltage ratings, a single tank 15A may be employed, as shown in FIG. 2. For the higher voltage ratings, separate tanks 15 may be utilized, as indicated in FIG. 1 of the drawings. For very high-power applications, where high rates-of-rise of the recovery-voltage transient are to be encountered, an impedance 80, such as shown in FIG. 11, may be utilized. The arrangement, as a result, is very flexible in being adaptable for various interrupting requirements.

Although the use of a high-dielectric-strength gas, such as SP has particularly desirable advantages because of the low pressure required and the light tank construction 15, however, for a cheaper breaker construction compressed air, at the tank pressure 3, may be employed within the tank 15, although due to the higher pressure a heavy thick-walled tank 15 may be necessitated.

Although there have been shown and described specific interrupting structures, it is to be clearly understood that the same were merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art without departing from the spirit and scope of the invention.

We claim as our invention:

1. A compressed-gas circuit interrupter including a reservoir containing a relatively inexpensive gas under pressure, an interrupting unit, contact means separable to establish an are within said unit, means utilizing a highpressure blast of gas from the reservoir to effect extinction of the arc and to exhaust to atmosphere, serially-related disconnecting switch means including a pair of cooperable disconnecting contacts, means separating said pair of cooperable disconnecting contacts to establish an isolating gap in the circuit, means defining a disconnecting switch enclosure surrounding said disconnecting switch means, means disposing said interrupting unit interiorly of said lisconnectin g switch enclosure, and another relatively highdielectric-strength gas having a higher dielectric strength than air disposed within said disconnecting switch enclosure.

2. A compressedgas circuit interrupter including a reservoir containing air under pressure, an interrupting unit, contact means separable to establish an are within said unit, blast-valve means utilizing a high-pressure blast of air from the reservoir to effect extinction of the arc and to exhaust to the atmosphere, serially-related disconnecting means including a pair of cooperable dis connecting contacts, means separating said pair of cooperable disconnecting contacts to establish an isolating gap in the circuit, means defining a disconnecting enclosure surrounding said disconnecting means, means positioning said interrupting unit interiorly of the disconnecting enclosure, and a relatively high-dielectric-strength gas having a higher dielectric strength than air disposed within said enclosure.

3. The combination in a compressed-air circuit interrupter of a grounded metallic interrupting casing, a pair of insulating casings joined to said grounded metallic interrupting casing adjacent opposite ends thereof, conducting rod means extending through each of said two insulating casings, terminal means disposed at the extremities of each of said insulating casings and connected to the respective rod means, a compressed-air interrupting unit insulatingly disposed interiorly of said grounded metallic interrupting casing, blast-valve means for utilizing a blast of compressed air to effect extinction of the arc established within said interrupting unit and to exhaust to the atmosphere, disconnecting means serially connected with one of said conducting rod means exteriorly of said unit and disposed within said grounded metallic interrupting casing, and a gas having a higher dielectric strength than air disposed within said casing encompassing said disconnecting means.

4. The combination in a compressed-air circuit interrupter of a grounded metallic interrupting casing, a pair of insulating casings joined to said grounded metallic interrupting casing adjacent opposite ends thereof, conducting rod means extending through each of said two insulating casings, terminal means disposed at the extremities of each of said insulating casings and connected to the respective rod means, a compressed-air interrupting unit insulatingly disposed interiorly of said grounded metallic interrupting casing blast-valve means for utilizing a blast of compressed air to effect extinction of the are established within said interrupting unit and to exhaust to the atmosphere, disconnecting means serially connected with one of said conducting rod means exteriorly of said unit and disposed within said grounded metallic interrupting casing, rotatable shaft means having an operating crank-arm for actuating said disconnecting means to the open and closed positions, and a gas having a higher dielectric strength than air disposed within said casing encompassing said disconnecting means.

5. A multi-pole compressed-air circuit interrupter including a grounded metallic tank, a plurality of compressed-air interrupting units disposed within said grounded metallic tank, a pair of oppositely-extending insulating casings extending outwardly from said grounded metallic tank and associated with each pole of the interrupter, conducting rod means extending through each of the two insulating casings for each pole, blast-valve means for sending a blast of compressed air to the interrupting unit of each pole for interrupting purposes and to exhaust to the atmosphere, disconnecting means associated, with each pole serially connected with one of the rod means for that pole and disposed within said tank, and a gas having a higher dielectric strength than air disposed within said tank adjacent said disconnecting means for each pole.

'6. The combination in a multi-pole compressed-air circuit interrupter of a grounded compressed-air tank, a plurality of conduits extending upwardly from the grounded compressed-air tank, a grounded metallic interrupting tank supported at least in part by said plurality of conduits, a plurality of compressed-air interrupting units disposed within said grounded metallic tank, a pair of oppositely-extending insulating casings extending outwardly from said grounded metallic tank and associated with each pole of the interrupter, conducting rod means extending through each of the two insulating casings for each pole, blast-valve means for sending a blast of compressed air to the interrupting unit of each pole for interrupting purposes and to exhaust to the atmosphere, disconnecting means associated with each pole serially connected with one of the rod means for that pole and disposed within said tank, and a gas having a higher dielectric strength than air disposed within said tank adjacent said disconnecting means for each pole.

7. A compressed-air circuit interrupter including a grounded compressed-air tank, a plurality of supporting feed pipes extending upwardly from said tank, a plurality of grounded interrupting casings supported at least partially by said upstanding feed pipes, a rotatable shaft means interconnecting the several tanks, disconnecting means operated by said rotatable shaft means disposed Within each interrupting casing, a compressed-air interrupting unit disposed within each interrupting casing, contact means separable to establish an are associated with each interrupting casing, and a dielectric gas having a higher dielectric strength than air disposed within each interrupting casing adjacent the respective disconnecting means.

8. A compressed-air circuit interrupter including means defining an interrupting casing, an interrupting unit including a reservoir of compressed air disposed interiorly Within said interrupting casing, disconnecting means also disposed within said interrupting casing and disposed in series relation with said interrupting unit, contact means Within said interrupting unit separable to establish an arc, blast-valve means utilizing a blast of compressed air to effect extinction of the arc and to exhaust to the atmosphere, means biasing the contacts to the closed position, means maintaining the disconnecting means open in the open circuit position of the interrupter, and a dielectric gas having a higher dielectric strength than air disposed within each interrupting casing adjacent the respective disconnecting means.

9. A compressed-gas circuit interrupter including a pressurized interrupting unit containing an inexpensive gas under pressure, contact means separable to establish an are disposed within said pressurized interrupting unit, an interrupting casing encompassing said pressurized interrupting unit and also enclosing disconnecting means, means electrically connecting said contact means with said disconnecting means, blast valve means for releasing a blast of said inexpensive gas from said pressurized interrupting unit across said established arc and out to the atmosphere to effect the extinction of the arc, and a gas having a higher dielectric strength than air disposed within said interrupting casing encompassing said disconnecting means.

10. A compressed-gas circuit interrupter including a pressurizedinterrupting unit containing an inexpensive gas under pressure, contact means separable to establish an arc disposed within said pressurized interrupting unit, means biasing said contact means to the closed position, an interrupting casing encompassing said pressurized interrupting unit and also enclosing disconnecting means, means electrically connecting said contact means with said disconnecting means, blast valve means for releasing a blast of said inexpensive gas from said pressurized interrupting unit across said established arc and out to the atmosphere to effect the extinction of the arc, and a gas having a higher dielectric strength than air disposed within said interrupting casing encompassing said disconnecting means.

11. A compressed-gas circuit interrupter including a pressurized interrupting unit containing an inexpensive gas under pressure, contact means separable to establish an are disposed within said pressurized interrupting unit, an interrupting casing encompassing said pressurized interrupting unit and also enclosing disconnecting means, means electrically connecting said contact means with said disconnecting means, blast valve means for releasing a blast of said inexpensive gas from said pressurized interrupting unit across said established arc and out to the atmosphere to effect the extinction of the are, a gas having a higher dielectric strength than air disposed within said interrupting casing encompassing said disconnecting means, and an impedance shunting said contact means to assist in circuit interruption.

12. A compressed-air circuit interrupter including a grounded compressed-air tank, a plurality of supporting feed pipes extending upwardly from said tank, a plurality of grounded interrupting casings supported at least para tially by said upstanding feed pipes, a rotatable shaft means interconnecting the several tanks, disconnecting means operated by said rotatable shaft means disposed Within each interrupting casing, a compressed-air interrupting unit disposed Within each interrupting casing, contact means separable to establish an are associated with each interrupting casing, and compressed air at tank pressure Within said grounded internupting casings for insulation strength at the disconnecting means.

References Cited by the Examiner UNITED STATES PATENTS 2,221,720 11/40 Prince 200-148 2,310,905 2/43 Bland-ford 200148 2,459,600 1/49 Strom 200-148 2,692,320 10/54 Leeds 200 2,970,198 1/61 Schrameck 200-l48 2,981,815 4/61 Leeds et al. 200 -148 FOREIGN PATENTS 582,599 11/46 Great Britain. 605,163 7/48 Great Britain.

KATHLEEN H. CLAFFY, Primary Examiner.

RICHARD M. WOOD, ROBERT K. SCHAEFER,

Examiners. 

1. A COMPRESSED-GAS CIRCUIT INTERRUPTER INCLUDING A RESERVOIR CONTAINING A RELATIVELY INEXPENSIVE GAS UNDER PRESSURE, AN INTERRUPTING UNIT, CONTACT MEANS SEPARABLE TO ESTABLISH AN ARC WITHIN SAID UNIT, MEANS UTILIZXING A HIGHPRESSURE BLAST OF GAS FROM THE RESERVOIR TO EFFECT EXTINCTION OF THE ARC AND TO EXHAUST TO ATMOSPHERE, SERIALLY-RELATED DISCONNECTING SWITCH MEANS INCLUDING A PAIR OF COOPERABLE DISCONNECTING CONTACTS, MEANS SEPASRATING SAID PAIR OF COOPERABLE DISCONNECTING CONTACTS TO ESTABLISH AN ISOLATING GAP IN THE CIRCUIT, MEANS DEFINING A DISCONNECTING SWITCH ENCLOSURE SURROUNDING SAID DISCONNECTING SWITCH MEANS, MEANS DISPOSING SAID INTERRUPTING UNIT INTERIORLY OF SAID DISCONNECTING SWITCH ENCLOSURE,AND ANOTHER RELATIVELY HIGHDIELECTRIC-STRENGTH GAS HAVING A HIGHER DIELECTRIC STRENGTH THAN AIR DISPOSED WITHIN SAID DISCONNECTING SWITCH ENCLOSURE. 